Stoker control



STOKER CONTROL 2 Sheets-Sheet FZiled Jan. 9, 1951 3 M a m WW m7 F 7 K fW W W H m f 5 W M 5 4'2 6 Z 2 2 7 M Z f/m W 5 w n 4 w I I.. Z .m w, q

TIT 3 ATTORNEYS.

Feb. 9, 1932. w. F. TROTTER I 1,844,615

STOKER CONTROL Filed Jan. 9, 1951 2 Sheets-Sheet 2 INVENTOR. W54 TE? ERant/e.

A TTORNEYS.

Patented F eb. 9,' 1932 I UNITED STATES,-

' I WALTER F. rnorrnn, or CINCINNATI, 01110, ASSIGNOR To HOLCOMIB & noxnMANU- A PATENT OFFICE FACTURING COMPANY, OF INDIANAPOLIS, INDIANA, ACORPORATION sroxaa CONTROL Application filed January 9,1931. Serial No.507,565.

This invention relates to a method and apparatus for combustion control.The invention is particularly applicable to Stoker-fired furnaces, butis also useful in other types of a combustion apparatus wherein the fuelis v mechanically supplied.

The principal object of the invention is to provide a method andapparatus for properly proportioning the amount of fuel sup- 1e pliedand the amount of air supplied by artificial draft for combustionpurposes. Heretofore it has been the practice,in installations wherein amechanical stoker and. an artificial draft are intermittently operated,it to operate the stoker and the draft fan simultaneously and for equalperiods of time; By that method, draft'is supplied only during the timethat fuel is fed to the furnace. As soon as the feeding of fuel stops,the supply at of artificial draft is also stopped. Unless the rate offuel supply and rate of air sup-' ply are accurately adjusted for agiven fuel, an amount of unburned fuel will be present in the'furnacewhen the draft supply is cut off. Since different fuels requiredifierent lengths of time and diderent amounts of air for their burning,such an arrangement, even when accurately adjusted, is only eficient forone type of fuel unless the rate of fuel supply or air supply may beadjusted with the change of fuel.

\ The principal feature of'the present invention consists in theprovision of a method and meansfor proportioning the length of time offuel feed and the length of time of draft supply rather thanproportioning the rates thereof. The stoker'is preferably operated for ashorter length of time for each operation than the fan and the drivingmechanisms for the fan and stolrer are interconnected in such mannerthat the stoker is operated a predetermined percentage of the time ofthe fan operation. Means are pro vided for conveniently varying thispredetermined percentage of time so that the proper proportion of fueland air is easily obtaiied for theparticular grade of fuel being useOther objects and features and the full nature of the invention Will beunderstood hill from the accompanying. drawings and the followingdescription and claims:

Figure 1 is a perspective view of a boiler having a furnace, a stokerand a forced draft fan. In this form of the apparatus, the fan 55 singlepower source is used for both the stoker and fan. Figure 6 is anelevational view of the apparatus used for proportioning the time ofstoker and fan operation with I the arrangement shown in Figured lln thedrawings there is shown a boiler 10 fitted with a fuel hopper 11'fromwhich fuel is supplied through a stoker housing 12 to the furnace of theboiler. contains any suitable form of feeding mechanism driven by amotor 13 through reduction gears contained in a gear box 14. Forceddraft is supplied to the furnace by means of a fan 15 driven by a motor16. A switch box 17 is mounted upon the motor 16 and contains a shaft 18driven from the motor by suitable gears contained in a gearbox 191 Theshaft 18 extends within the switch The housing 12 box 17 and hasfastened'thereto a cam 20 having a projection 21 formed thereon. A cam22 having a projection 23 is also carried upon the shaft 18 but is freefor both longitudinal and rotational movement with respect thereto. Thecam 22 is fitted with openings 2t engaging pins 25 carried by the cam20. en the said pins and openings are engaged, therefore, the cams 20and 22 rotate in unison with the shaft 18. The engagement .of the saidpins and openings is maintained by a spring 26 carried within the hub ofcam 22 and abutting against a collar 27 threadedly fastened upon theendof the shaft 18. By this means, the cam 22 may be manually drawnbackward upon the shaft 18 and rotated to bring the pins 25 intoengagement with the open- Elli Milt

ings 24 in such manner as to place the projections 21 and 23 in anydesired angular relation with respect to each other. A slide 28 issupported upon bosses 29 by means of screws 30 engaging longitudinalopenings 31 in the said slide. As will be seen from Figure 3, the slide28 is so placed as to have the projection 21 upon one side and theprojection 23 upon the opposite side thereof. Upon one side of the slide28 there is formed a projection 32 adapted to be engaged by theprojection 23. Upon the opposite side is formed a projection 33positioned to be engaged by the projection 21. By this means therotation of shaft 18 moves the slide to the left in Figure 2 whenprojection 23 engages projection 32 and returns the said slide to theright when projection 21 engages projection 33. Since the projections 21and 23 may be set at any desired angular relation, the slide 28 may bemaintained in the left hand or right hand position any desiredpercentage of the time of rotation of shaft 18. j

A mercury switch 34 is carried upon a lever 35 pivotally mounted bymeans of a screw 36 within the switch box 17 The opposite end of thelever 35 engages an opening 37 in the slide 28. By this means themovements of the said slide to right and left alternately tilt themercury switch 34 into opencircuit and closed-circuit positions. Themercury switch 34 has connected thereto electrical connections 38leading to a motor controller 39 adapted to start and stop the motor13bymeansofelectricalconnections40. These electrical connections and themotor controller are such that the motor 13'may be operated only whenthe mercury switch 34 is in closedcircuit position. c

In the form of apparatus shown in Figure 4, the fan motor 16 iscontrolled by a controller 41 connected thereto by conductors 42. Thecontroller 41 isconnected by conductors 43 with a pressure-operatedswitch 44 of any when the boiler pressure is above this desiredpressure. Conductors 46 supply power to controller 39 from any suitablepower source.

ower is in turn supplied from controller 41- to controller 39 byconductors 46a only when controller 41 is actuated by the closing of thecircuit in switch 44 so that the stoker motor 13 can operate only duringoperation of thefan motor 16. By this means the fan motor 16 is operatedonly when it is necessary to lncrease the furnace temperature to bringthe boiler pressure up to normal. The stoker motor 13 and the stoker areoperated only durmg a predetermined percentage of the time of operationof the fan motor 16 and are stopped during the remainder of fan motoroperation and when the fan motor is not in operation. This predeterminedpercentage of time is determined by the angular position of theprojections 21 and 23 in the switch box 17. This angular position isindicated by an index arrow 47 marked upon the collar 27 and registeringwith index numbers 1 to 12 carried upon a flange 48 formed upon the hubof cam 22. For example, if it is desired to run the stoker fifty percentof the time of fan operation or six minutes out of every twelve minutesof the fan operation, the arrow 47 is set to the index number 6. Themercury switch 34 will then be moved to closed-circuit position sixminutes out of every twelve minutes of fan operation.

In the form of apparatus shown in Figure 5, a boiler 110 receives fuelfrom a fuel hopper 111 through stoker housing 112. A mo-' tor 113 drivesthe said stoker through a clutch 149 in a housing 150 and suitable gearsin a gear box 114. The clutch 149 may be thrown into operative andinoperative positions by a lever 151 controlled by a mechanism 152similar in all important respects to the mechanism previously describedfor controlling the mercury switch 34. This mechanism 152 is driven by aworm 153 and a.

quired. The mechanism 152 operates the clutch 149 to drive the stoker adesired percentage of the time of operation of the motor 113. It is tobe noted that while the mechanism 152 is of the same general form asthat for operating the mercury switch 34, the parts must be of heavierconstruction because of the heavier duty required thereof.

In the operation of the method and apparatus herein described a largerquantity of fuel is fed to the furnace at each stoker operation than isimmediately required.

After the feeding of fuel ceases, the fan continues to operate as longas an increase of furnace temperature is required. If this period islonger than that required for one complete revolution of shaft 18,another period of fuel feeding is initiated. If the heating requirementsdo not require the operation of stoker and fan, such operation ceasesand is again taken up at the point of cessation when heatingrequirements again increase.

While the foregoing specifications describe the invention as applied toa-boiler in such manner as to maintain a predetermined boiler pressure,it evident that it can also be applied to heaters for other purposes. Asapplied to a heater, a thermostatic switch is substituted for thepressure-operated switch 44. The said switch then operates the apparatusto maintain a predetermined temperature rather than a predeterminedpressure.

The invention claimed is:

1. Combustion control apparatus for a furnace including intermittentlyoperable draft apparatus adapted to supply draft at a substantiallyconstant rate when operating to said furnace, a stoker adapted to supplyfuel -.draft apparatus adapted to supply draft to said furnace at asubstantially constant rate when operating, a stoker adapted to supplyfuel to said furnace. mechanism for automatically starting said draftapparatusin response to a requirement for increase furnace temperatureand for automatically stopping the same when said increased furnacetemperature is no longer required, a sourceof power for said stoker, andmeans for connectlng said power source and sald stoker for supplymgfuel, said means being automatically operable a predetermined percentageof the time of operation of said draft apparatus.

3. Combustion control apparatus for a boiler furnace includingintermittently operable draft apparatus adapted to supply draft to saidfurnace at a substantially constant rate when operating, a stokeradapted to supply fuel to said furnace, control mechanism forintermittently operating said draft apparatus inautomatic response tovaiiations stoker, and means for connecting said power said means beingautomatically operable a predetermined percentage of the time ofoperation of said draft apparatus.

4. Combustion control apparatus for a furnace including intermittentlyoperable draft apparatus adapted to supply draft to 1 said furnace at asubstantially .constant rate when operating, a stoker adapted to supplyfuel to said-furnace, a motor for driving said draft apparatus, a secondmotor for driving said stoker, regulating means for intermittentlyoperating said draft motor in' automatic response to furnace heatingrequirements, control means for stopping and starting said stoker motor,and mechanism driven by said draft motor and adapted to actuate saldcontrol meansto operate said stoker motor a predetermined percentage ofthe time of operation of said draft motor. 5. Combustion, controlapparatus for a furnace including intermittently operable draftapparatus adapted to supply draft to sald furnace at a substantially.constant rate while operating, a stoker adapted tosupply fuel to saidfurnace, a motor for driving said draft apparatus and stoker, said motorbeing permanently connected to said draft apparatus, a clutch forintermittently connectin said motor and said stoker, regulating meansfor intermittently operating said motor in automatic response to furnaceheating requirements, and mechanism driven by said motor and adapted toactuate said clutch-a predetermined percentage of the time of operationof said motor. 1

6. A method of combustion control for stoker-fired furnaces includingintermittently supplying draft at a substantially constant rate inautomatic response to heating requirements, and automatically operatingthe stoker to supply fuel a predetermined percentage of the time duringwhich said draft is supplied.

' 7. A method of combustion control for stoker-fired boilers'includingintermittently supplying draft at a substantially constant rate inautomatic response to variations in V boiler pressure, and automaticallyoperating a stoker to supply fuel a predetermined percentage of the timeduring is supplied.

ltn witness whereof, I have hereunto affiXed my signature. A

WALTER F. TRUTTER.

in boiler pressure. a source of power for said i source and said stokerfor supplying fuel, 116

which said draft

